Measuring the dark universe. Luca Amendola University of Heidelberg

Transcription

1 Measuring the dark universe Luca Amendola University of Heidelberg 1

2 In search of the dark Searching with new probes Searching in new domains Or: a short overview of what I have been doing in the last couple years beside Euclid L. Amendola, 09/2018 2

3 In search of the dark Searching with new probes 21cm GWs Searching in new domains PBH L. Amendola, 09/2018 3

4 Searching with new probes So far, cosmology has been essentially CMB+LSS+WL+SNIa+Clusters Insufficient to break all the degeneracies and probe intermediate redshifts New probes: 21cm, GWs, polarization in CMB,,new distance indicators, redshift drift, L. Amendola, 09/2018 4

5 Observing Hydrogen H 2 (molecular hydrogen) difficult to observe (no optical/radio lines, no dipole, etc) HII (ionized hydrogen) free-free (Bremsstrahlung) + free-bound (recombination) HI (atomic hydrogen) hyperfine spin-flip at 21cm L. Amendola, 09/2018 5

6 Observing HI HI hyperfine spin-flip at 21cm, not absorbed by dust: we can measure redshift in galaxies and before/during reionization! redshift MHz MHz 20 70Mhz frequency (CMB=160 MHz) L. Amendola, 09/2018 6

7 Observing HI HI hyperfine spin-flip at 21cm + not absorbed by dust: we can measure galaxy Doppler redshift! 7 Andromeda galaxy L. Amendola, 09/2018 Chemin et al. 2009

8 Intensity Mapping HI hyperfine spin-flip at 21cm + not absorbed by dust: we can measure redshift before reionization! Intensity Mapping (Chang et al 2008, Wyithe & Loeb 2008): HI from large-scale structure rather than galaxies up to z=50: Epoch of Reionization z=6-10 Experiments: GMRT, LOFAR, MWA, PAPER, 21CMA, GBT, CRT, CHIME Just like CMB, but in 3D! SDSS Euclid 8 Tegmark & Zaldarriaga 2008

9 Square Kilometer Array 1 sq. km area radio-telescope

10 Intensity Mapping Estimate of the expected 21cm flux (21cmFAST * ) Linear perturbations are evolved with Zeldovich approx at z>>1 regions above a certain threshold are ionized (so no HI) 21cm emission from HI relative to CMB photons spin - CMB temperature reionization parameters: mean free path, halo virial temperature, ionization efficiency * github.com/andreimesinger/21cmfast

11 Intensity Mapping Y = 1.01 Y = 1 Y = 0.99 z=10 z=7 ionized 21cm Heneka and L.A

12 Intensity Mapping We consider wcdm plus a modified gravity parameter Y assumed constant within the relevant epochs This affects the linear matter perturbation equation L. Amendola, 09/2018

13 21cm power spectrum Forecasts for SKA 1 z=10 non-lin z=7 L. Amendola, 09/2018

14 21cm forecasts Forecasts for SKA 1, z=6 to z=11 Forecasts for SKA 1 Parameters L. Amendola, 09/2018

15 21cm forecasts Current data, z=0 to z=1 Forecasts for SKA 1, z=6 to z=11 Y Taddei, Martinelli, L.A. et al Y Parameters Heneka and L.A

16 21cm forecasts Forecasts for SKA 1 Y L. Amendola, 09/2018

17 21cm forecasts 21cm: unique probe of the Universe at high redshift highly sensitive to the linear growth strong constraints on Y at redshifts much larger than with SNIa or galaxy clustering/weak lensing L. Amendola, 09/2018

18 GW as standard sirens L. Amendola, 09/

19 GW as standard sirens Amplitude of GW measure luminosity distance with GW chirps measure redshift with optical counterparts L. Amendola, 09/

20 GW as standard sirens Amplitude of GW Distribution of GW events with LISA Tamanini 2017 L. Amendola, 09/

21 GWs in non-standard gravity!! h + 3H(1+ α M )! h + (1+ α T )k 2 h = 0 GW-distance L.A. et al L. Amendola, 09/

22 More from GWs Lensing of GWs ISW of GWs Power spectra of GWs GW backgrounds L. Amendola, 09/

23 Searching in new domains Dark matter and dark energy are not dark but transparent The evolution of the Universe before decoupling is however really dark! Only two almost direct probes so far: BBN and CMB BB spectrum What else: B-modes, PBHs, non-gaussianity? really-dark age dark age L. Amendola, 09/

24 Gravitational wave speed CT varying c 2 T =1+α T l(l+1)c l BB /2π [µk 2 ] fast ΛCDM, r 0.05 = 0 ΛCDM, r 0.05 = 0.2 a 1 = 0.8, r 0.05 = 0.2, c T 2 = 1.7 a 1 = 1, r 0.05 = 0.2, c T 2 = 1 a 1 = 1.5, r 0.05 = 0.2, c T 2 = 0.5 a 1 = 2, r 0.05 = 0.2, c T 2 = 0.3 slow multipole L. Amendola, 09/2018 L.A., G. Ballesteros, V. Pettorino, 2014 See also Raveri, Silvestri and Zhou,

25 PBH after inflation PBH are normally assumed to form from spectral peaks due to features in slow-rolling inflation Eg inflection in the potential P ~ H 2 ε L. Amendola, 09/ Garcia-Bellido & Ruiz Morales 2017,

26 Growth during radiation era? Matter growth equations Perturbation do not grow because δ m ''+ (1+ H ' H )δm' 3 2 (Ω mδ m + Ω r δ r ) = 0 Ω m 0 δ r 0 L. Amendola, 09/

27 interacting fields Interacting fields ψ (heavy) and ϕ (light) coupling EOM L. Amendola, 09/

28 interacting fields EOM 1 Ω ψ = 1 3β 2 Ω φ = 1 6β 2 W f y bar rad f-kin standard cosmology L.A., C. Wetterich and J. Rubio N see also Bonometto & Mainini 2016

29 Growth during radiation era! δ m ''+ (1+ H ' H )δm' 3 2 (Ω mδ m + Ω r δ r ) = 0 Y = 1+β 2 If a particle ψ strongly interacts with coupling β>>1 with a field ϕ, perhaps dark energy, then there are two consequences: 1) The effective gravitational force is large ( Y = 1+β 2 >> 1 ) 2) The amount of ψ during radiation is larger (Ω r >>Ω χ >> Ω bar ) L. Amendola, 09/

30 Growth during radiation era Growth as δ χ ~ a 1.6 after horizon reenter during radiation: formation of BHs or DM-balls Simple relation between BH mass and coupling parameter β L.A., C. Wetterich and J. Rubio

31 Growth during radiation era No need of special features on the inflationary spectrum Do these objects become BHs or do they virialize into DM-balls? Is the coupling fully screened? If DM-balls, they escape the strong constraints on PBHs Dark matter ψ remains confined into these structures 31

32 In search of the dark Searching with new probes 21cm GWs Searching in new domains PBH L. Amendola, 09/

33 Conclusions there s more darkness to discover out there! 33 33